Improvement in coffin-screws



F. W. CABOT.

COFFIN-SCREW. No.169,889. Patented Nov. 16,1875.

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FERDINAND W. OABOT, OF MANSFIELD,'MASSAUHUSETTS.

IMPROVEMENT IN COFFlN-SCREWS.

Specification forming part of Letters Patent N 0. 169.889, dated November 16, 1875; application filed October 28, 1875.

To all whom it may concern:

Be it known that I, FERDINAND W. GABOT, of Mansfield, of the county of Bristol, of the State of Massachusetts, have invented a new and useful Improvement in what are termed Coffin-Lid Screws; and do hereby declare the same to be fully described in the following specification and represented in the accompanying drawings, of which- Figurel is a top view, Figs. 2 and 3 side views, and Figs. 4: and 5 longitudinal sections, of one of my improved screws.

My invention relates to such screws as have hollow or chambered heads, composed of two metallic domes or cups, united at their bases, and having the screw-shank projecting from the inferior or lower of said domes, such screwshank, previous to my invention, though fastened to'the lower, not having been extended up to the upper, of said domes. In consequence of this such dome was supported only at its base, whereas, by myimprovement, it is supported also at its crown, so that it cannot be readily crushed or broken down by a blow or weight upon such crown. Furthermore, the upper dome is provided with a pyramidal or prismatic mortise or recess, to receive a correspondingly-shaped head, made or formed on the upper extension of the screw-shank, such being to prevent the connection of the head and the shank from being impaired or broken, so as to allow of the head being revolved on the shank during an attempt to screw the shank into a lid or article, or to unscrew it therefrom. Furthermore, the upper dome or cup is provided with a pyramidal or prismatic handle, to be grasped by the thumb and finger of a person while revolving the screw.

In the drawings, A denotes the screw-shank, furnished with a helical thread, a, and a chambered head, B, this latter being composed of the two separate hollow cups or domes e d, arranged as shown and united at their bases. The screw-shank A extends through the lower of the said domes at its crown, and up the inner surface of the crown of the upper dome,

such shank being soldered 0r fastened to the lower dome. Furthermore, the shank has a prismatic pyramidal or elongated head, 6, to enter a corresponding mortise or recess, f, in the upper dome, or in an extension, g, therefrom, such mortise or recess and head being for the purpose hereinbefore mentioned. The extension 9, also pyramidal or prismatic or of an analogous shape, as shown, constitutes the aforesaid handle.

Fig. 6 is a side View of the screw-shank, Figs. 7 and 8 being transverse sections of the upper dome of the head B, they being taken in planes at right angles to each other.

I claim, as my invention or improvement in the chambered headed screw, having its head formed of two concavo convex parts or domes, connected together at their edges, as set forth 1. The screw-shank A, as fastened to the base portions 0, and extended up therefrom to and against the cup portion d, so as to constitute a support thereto.

2. The screw-shank A, secured in the base 0 of the head B, and extended in opposite directions therefrom, and provided with the tenon or head 0, as described, in combination with the dome-cup d, provided with. the corresponding mortise or recess f, and having the said head 6 arranged in said recess, as and for the purpose or purposes explained.

3. The dome-cup 61, provided with the handle or device g, for aid in effecting rotation of the screw, as described.

4. The dome-cup at, having the handle g and mortise or recess f, in combination with the base portion 0, and with the screw-shank A, fastened to the said base portion 0, and extended in opposite directions therefrom, and provided with the tenon or head 6, arranged in said mortiseor recess f, all being as set forth.

FERDINAND W. GABOT. 

